Semiconductor devices are commonly found in modern electronic products. Semiconductor devices vary in the number and density of electrical components. Discrete semiconductor devices generally contain one type of electrical component, e.g., light emitting diode (LED), small signal transistor, resistor, capacitor, inductor, and power metal oxide semiconductor field effect transistor (MOSFET). Integrated semiconductor devices typically contain hundreds to millions of electrical components. Examples of integrated semiconductor devices include microcontrollers, microprocessors, and various signal processing circuits.
Semiconductor devices perform a wide range of functions such as signal processing, high-speed calculations, transmitting and receiving electromagnetic signals, controlling electronic devices, transforming sunlight to electricity, and creating visual images for television displays. Semiconductor devices are found in the fields of entertainment, communications, power conversion, networks, computers, and consumer products. Semiconductor devices are also found in military applications, aviation, automotive, industrial controllers, and office equipment.
Semiconductor devices exploit the electrical properties of semiconductor materials. The structure of semiconductor material allows the material's electrical conductivity to be manipulated by the application of an electric field or base current or through the process of doping. Doping introduces impurities into the semiconductor material to manipulate and control the conductivity of the semiconductor device.
A semiconductor device contains active and passive electrical structures. Active structures, including bipolar and field effect transistors, control the flow of electrical current. By varying levels of doping and application of an electric field or base current, the transistor either promotes or restricts the flow of electrical current. Passive structures, including resistors, capacitors, and inductors, create a relationship between voltage and current necessary to perform a variety of electrical functions. The passive and active structures are electrically connected to form circuits, which enable the semiconductor device to perform high-speed operations and other useful functions.
Semiconductor devices are generally manufactured using two complex manufacturing processes, i.e., front-end manufacturing and back-end manufacturing, each involving potentially hundreds of steps. Front-end manufacturing involves the formation of a plurality of die on the surface of a semiconductor wafer. Each semiconductor die is typically identical and contains circuits formed by electrically connecting active and passive components. Back-end manufacturing involves singulating individual semiconductor die from the finished wafer and packaging the die to provide structural support, electrical interconnect, and environmental isolation. The term “semiconductor die” as used herein refers to both the singular and plural form of the words, and accordingly, can refer to both a single semiconductor device and multiple semiconductor devices.
One goal of semiconductor manufacturing is to produce smaller semiconductor devices. Smaller devices typically consume less power, have higher performance, and can be produced more efficiently. In addition, smaller semiconductor devices have a smaller footprint, which is desirable for smaller end products. A smaller semiconductor die size can be achieved by improvements in the front-end process resulting in semiconductor die with smaller, higher density active and passive components. Back-end processes may result in semiconductor device packages with a smaller footprint by improvements in electrical interconnection and packaging materials.
A conventional semiconductor wafer may contain conductive through-silicon vias (TSV). TSV provide vertical electrical connection through semiconductor die in three-dimensional (3D) integration of semiconductor packaging. A plurality of vias is formed through the semiconductor wafer. The vias are filled with conductive material to form the conductive TSV. Conductive TSV formed partially through a semiconductor wafer are revealed or exposed by removing a portion of the semiconductor material using a backside via reveal (BVR) process. Current BVR processes involve multiple processing steps including multiple chemical mechanical polishing (CMP) steps, silicon etching, multiple passivation processes, photolithography, and passivation etching.
CMP is an expensive manufacturing process, and the multiple CMP steps involved in current BVR processes increase the cost of manufacturing the semiconductor devices. The CMP process is inadequate for processing wafers having different thicknesses and different TSV depths. Alternatively, a portion of the back surface of the semiconductor wafer is removed by a photolithographic etching process with a 1× stepper to expose a portion of the side surface of the conductive TSV. The 1× stepper typically cannot provide sufficient overlay margin for the photolithographic and etching process. Current BVR processes are limited in capability to process different wafer thicknesses and different TSV depths. Thus, current BVR processes are not economical for mass production.